8. Terrain & Obstacle Data Collection – Area 3 1. Data on terrain and obstacles that extend more than a half-metre (0.5 m) above the horizontal plane passing through the nearest point on the aerodrome/heliport movement area shall be collected and recorded. 2. Terrain and obstacle data in Area 3 shall be collected and recorded in accordance with numerical requirements specified in Table A8-1 and Table A8-2, respectively.
9. Terrain Data Collection Surface – Area 4 Only terrain data shall be collected and recorded in Area 4 in accordance with the numerical requirements specified in Table A8-1.
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14. Statistics ! Dark blue is less than one standard deviation from the mean. For the normal distribution , this accounts for 68.27 % of the set; while two standard deviations from the mean (medium and dark blue) account for 95.45%; three standard deviations (light, medium, and dark blue) account for 99.73%; and four standard deviations account for 99.994%. The two points of the curve which are one standard deviation from the mean are also the inflection points . Source: < http://en.wikipedia.org/wiki/Standard_deviation > z σ percentage within CI percentage outside CI ratio outside CI 1 σ 68.2689492% 31.7310508% 1 / 3.1514871 1.645 σ 90% 10% 1 / 10 1.960 σ 95% 5% 1 / 20 2 σ 95.4499736% 4.5500264% 1 / 21.977894 2.576 σ 99% 1% 1 / 100 3 σ 99.7300204% 0.2699796% 1 / 370.398 3.2906 σ 99.9% 0.1% 1 / 1000 4 σ 99.993666% 0.006334% 1 / 15788 5 σ 99.9999426697% 0.0000573303% 1 / 1744278 6 σ 99.9999998027% 0.0000001973% 1 / 506800000 7 σ 99.9999999997440% 0.0000000002560% 1 / 390600000000